Natural Resources Assessment, Inc.

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1 Malibu Lagoon Enhancement and Restoration Plan Malibu, California Prepared for: ENVICOM Agoura Road Agoura Hills, California Prepared by: 3415 Valencia Hill Drive Riverside, California October 6, 2005 Project Number: ENC Valencia Hill Drive, Riverside, California Telephone Fax

2 CERTIFICATION I hereby certify that the statements furnished below and in the attached exhibits present data and information required for this biological evaluation, and that the facts, statements, and information presented are true and correct to the best of my knowledge and belief. This report was prepared in accordance with professional requirements and recommended protocols for small mammal trapping studies. Karen Kirtland Date October 6, 2005 October 6, 2005 Malibu Mouse ENC i

3 Table of Contents Page Executive Summary...S Introduction Site Location and Project Description Methods Data Review Small Mammal Survey Results Data Review Field Surveys Discussion References Personal Communication List of Figures 1 Regional Vicinity and Project Site Map Plant Communities Trapline Locations...9 List of Tables 1 Trapping Results for Malibu Lagoon...13 Site Photos 1 Hiking trail in willow/atriplex scrub habitat Mud flat/mulefat scrub ecotone Coastal salt marsh/freshwater marsh Mulefat scrub. Note density of scrub and ground cover Southern coastal salt marsh Mixed scrub habitat Sandy ecotone between beach and scrub habitat October 6, 2005 Malibu Mouse ENC i

4 Executive Summary (NRA, Inc.) conducted a small mammal trapping study for the proposed Malibu Lagoon Enhancement and Restoration Plan replacement in the city of Malibu. The purpose of the survey was to identify the small mammal species present within the boundaries of the Lagoon. Malibu Lagoon is a 31 acre shallow water embayment along the Pacific Coast at Malibu. It forms the terminus of the Malibu Creek Watershed draining into Santa Monica Bay. The site was assessed by a walking survey. Notes were taken on the condition of the site, the habitats present, soil types and other factors. This information was used to determine the location of traplines and placement of traps. Site photographs were taken with a digital camera. The trapping study was conducted according to standard protocols developed for small mammal trapping work. Trapping results were very poor, with only two species being caught. One black rat and one savannah sparrow were trapped. Based on the field survey and the trapping results, the Malibu Lagoon provides very poor quality habitat for small mammals. Most of the available scrub habitat is very dense at ground level as well as higher up, and the southern coastal salt marsh is almost entirely covered by pickleweed (Salicornia virginica) with very little bare ground exposed. Small mammals generally prefer more open scrub habitats with low openings and sparse ground cover. In addition, the Lagoon is almost entirely surrounded by either water (open ocean) or development (housing and commercial). Malibu Creek provides the only connection to upland habitats, and it is severely restricted as it crosses under the Pacific Coast Highway. It is possible that other species, such as the deer mouse and the meadow mouse, are present in the Lagoon, but are at such low numbers that capture is difficult. It is also possible that more species of small mammal exist in the upland areas around Malibu Creek, but only infrequently come onto the Lagoon to forage. October 6, 2005 Malibu Mouse ENC S-1

5 1.0 Introduction (NRA, Inc.) conducted a small mammal trapping study for the proposed Malibu Lagoon Enhancement and Restoration Plan replacement in the city of Malibu. The purpose of the survey was to identify the small mammal species present within the boundaries of the Lagoon. 2.0 Site Location and Project Description Malibu Lagoon is a 31 acre shallow water embayment along the Pacific Coast at Malibu (Figure 1). It forms the terminus of the Malibu Creek Watershed draining into Santa Monica Bay. The lagoon is in Section 32 (estimated), Township 1 South, Range 17 west, of the Malibu (1995) 7.5' U.S. Geological Survey (USGS) topographic quadrangle, San Bernardino base and meridian (Figure 1). The proposed project is the enhancement and restoration of Malibu Lagoon (Figure 2). 3.0 Methods 3.1 Data Review A data review was conducted to provide information on plant and wildlife species known occurrences within the vicinity. This review included biological texts on general and specific biological resources, including those resources considered to be sensitive by various wildlife agencies, local governmental agencies and interest groups. List of sensitive biological resources provided by the California Natural Diversity Data Base Biological resources report for this site and adjacent properties General texts and other documents identifying potential resources on the property NRA, Inc. also reviewed other available technical information on the biological resources of the site. We used the information to focus our survey efforts in the field. 3.2 Small Mammal Surveys Focused surveys for small mammals were conducted by Ms. Karen Kirtland from September 13 through September 16, Trapping surveys were conducted according to standard protocols for small mammals. Four lines of traps were used. Two lines had 20 traps, and two lines had 30 traps. Each trap line was set for three days. Trap lines were placed in all areas containing suitable soils and vegetation for small mammals. The purpose was to sample all suitable native habitat types. Each trap was baited with a mixture of October 6, 2005 Malibu Mouse ENC

6 Project Site Miles (approximate) Source: Malibu USGS topographic quadrangle Figure 1 Regional Vicinity and Project Site Map N Feet (approximate) Malibu Lagoon Restoration and Enhancement Project Small Mammal Trapping Assessment Malibu, California October 6, 2005 Malibu Mouse ENC

7 Source: Merkel & Associates 2004 Figure 2. Plant Communities Map Malibu Lagoon Restoration and Enhancement Project Small Mammal Trapping Assessment Malibu, California October 6, 2005 Malibu Mouse ENC

8 birdseed placed at the back of the traps. The traps were left in place and opened at dusk each night and inspected at dawn each morning. All animals were identified and released at the point of capture. Photographs were taken of the habitat conditions. Notes were made on the site conditions at each trap line. Weather conditions at the time of the trapping were also noted. 4.0 Results 4.1 Data Review Mammals described as being found in salt marshes include California meadow mice (Microtus californica), house mice (Mus musculus), and deer mouse (Peromyscus maniculatus). Most of these species seem to survive on a diet of salt marsh plants (mainly pickleweed) combined with upland seed (Bertness et al 1987, Johnston 1956, Reichman and Price 1993, Zeiner et al 1990 ). Shrews (Sorex spp.) also live in salt marsh, but shrews feed predominantly on small invertebrates rather than seed or other plant material (Grinnell 1933, Ingles 1965). Based on the literature and discussions with experts, it appears that small mammals from upland areas will forage in the marsh habitat for seed and other food sources, but seldom reside entirely within the marsh habitats (Dr. Brad Blood, personal communication September 16, 2004, Mr. Philippe Vergne, personal communication, September 15, 2005). 4.2 Field Surveys Weather Conditions Morning weather conditions during the surveys were as follows: September 14, Skies overcast, with temperatures in the sixties (degrees Fahrenheit) and winds from two to five mile per hour from the east. September 15, The skies were clear, with temperatures in the high sixties and winds at ten to fifteen miles per hour from the east. September 16, The skies were overcast, with temperatures in the low sixties and winds at five to ten miles per hour Topography and Soils The Lagoon is flat, with a mixed topography typical of fresh and saltwater marshes. The soils are predominantly a hard packed sand covered by loose sand in some areas Land Uses The lagoon is relatively free from human disturbance, with the exception of the beach area and hiking trails. October 6, 2005 Malibu Mouse ENC

9 4.2.4 Disturbances Disturbances on site include hiking, fires, homeless sites, and occasional unauthorized trespass into restricted areas Plant Communities The following descriptions are taken directly from Malibu Lagoon Vegetation Communities And Wetland Delineation (Merkel & Associates 2004) Southern Willow Scrub Southern willow scrub was mapped in the northwestern portion of the study site, near the State Beach parking lot. This habitat generally consisted of mature arroyo willow (Salix lasiolepis), with occasional mule fat (Baccharis salicifolia), and quail saltbush (Atriplex lentiformis ssp. lentiformis). The southern willow scrub immediately adjacent to the parking lot entrance may have been planted and sustained by irrigation or runoff from Pacific Coast Highway, rather than by Malibu Lagoon. This distinction is important when determining jurisdictional wetland boundaries Atriplex Scrub This habitat was found primarily along the trails leading from the parking lot to the beach and is composed predominantly of quail saltbush, with occasional coyote brush (Baccharis pilularis), mulefat, toyon (Heteromeles arbutifolia), California sagebrush (Artemisia californica), and elderberry (Sambucus mexicana). Also occurring were giant coreopsis (Coreopsis gigantea) and showy island snapdragon (Galvesia speciosa), species naturally occurring on the Channel Islands, but frequently included in revegetation programs. Non-native elements included Myoporum (Myoporum laetum), black mustard (Brassica nigra), and hottentot fig (Carpobrotus edulis). The quail saltbush generally formed dense shrubs, several meters in height and width, and occurred in drier, high areas fringing the marsh and access trails. The large area of Atriplex scrub occurred in sandy soils immediately north of the beach, on the south side of the lagoon. The quail saltbush was very tall, occasionally interspersed by California sagebrush and coyote brush Baccharis Scrub This upland vegetation community was mapped along the western edge of the study site, to the east of the access road that skirts the Lagoon. The habitat was dominated by coyote brush, and also included mule fat, quail saltbush, and St. Catherine s lace (Eriogonum giganteum). St. Catherine s lace is native to the Channel Islands and was likely planted at Malibu Lagoon as part of previous revegetation efforts Mule Fat Scrub Areas dominated by mule fat scrub occurred on the margins of the lagoon in between areas of southern willow scrub, Baccharis scrub, and Atriplex scrub. The mule fat was occasionally interspersed with October 6, 2005 Malibu Mouse ENC

10 quail saltbush and coyote brush. There is also a large area of mule fat scrub along the trail leading from the parking lot to the beach. This may have been part of earlier revegetation efforts. The mule fat scrub mapped north of the parking lot entrance may have been planted and may be the sustained by irrigation or runoff from Pacific Coast Highway, rather than by Malibu Lagoon Venturan Coastal Sage Scrub This vegetation type occurred only in very small amounts, primarily along the trail leading to the beach. These areas were likely planted as part of past restoration efforts. Dominant species included California sagebrush and St. Catherine s lace. Mixed in were giant coreopsis and showy island snapdragon. North of the parking lot was another small area of coastal sage scrub composed nearly entirely of laurel sumac (Malosma laurina) Mixed Scrub This vegetation type was used to map slightly atypical areas north of the access road on the southwest side of the lagoon. This area contained a variable mix of predominantly native species, with elements of at least four of the habitat types described above. The two dominant species were coyote brush and mule fat, with quail saltbush being the next most abundant shrub. Also regularly psilostachya) and California sagebrush. This variety of co-occurring species (such as mule fat, which is a wetland indicator species, and coastal sage scrub elements, an upland habitat) again suggests that this may be the site of past restoration efforts. Degraded fencing and irrigation materials were also evident in these areas Southern Coastal Salt Marsh Southern coastal salt marsh was the most abundant, vegetated habitat within Malibu Lagoon. This habitat was dominated by salt grass (Distichlis spicata), pickleweed (Salicornia virginica,) and marsh jaumea (Jaumea carnosa). Other common species included salt marsh dodder (Cuscuta californica) and alkali heath (Frankenia salina). This vegetation type occurred at the lowest elevations, generally fringing the mudflat. This habitat likely expands and contracts over time with seasonal inundation and dewatering of the lagoon. Slightly higher portions of the coastal salt marsh that would more rarely experience inundation also supported areas of quail saltbush shrubs. The coastal salt marsh vegetation persisted as an understory however, so these areas were also mapped as coastal salt marsh. In many places the coastal salt marsh was also infested by invasive exotics, primarily perennial pepperweed (Lepidium latifolium). Perennial pepperweed is highly invasive and difficult to control. It is, however, intolerant of prolonged periods of inundation during the growing season; perhaps restoration of the lagoon to more natural hydrologic conditions will assist in controlling this weed. The marsh also supported occasional patches of the invasive exotic hottentot fig (Carpobrotus edulis), black mustard (Brassica nigra), and giant reed (Arundo donax). October 6, 2005 Malibu Mouse ENC

11 Coastal and Valley Freshwater Marsh Coastal and valley freshwater marsh occurred primarily in a large area south of the parking lot, fringing pools of open freshwater. This vegetation type was predominantly composed of two species of bulrush (Scirpus californicus and Scirpus acutus) and formed tall dense stands of vegetation. This vegetation had expanded into areas of open water visible in the aerial photograph used in the field and in Figure 2. A few additional small areas of freshwater marsh were also mapped near freshwater sources, such as the drain outlet in the southwest corner of the lagoon Brackish Marsh Brackish marsh was mapped on the east shore of the lagoon, immediately above the mudflat. The mixture of salt marsh and freshwater marsh species reflects the variable salinities that occur in the lagoon as a result of variable hydrological conditions. This area was dominated by salt grass, regularly interspersed with bulrush. Also mixed in were marsh jaumea, pickleweed, salt marsh dodder, and mulefat. A patch of salt cedar (Monanthochloe littoralis), an invasive exotic, was found adjacent to the fence bordering the lagoon. Perennial pepperweed also occurred in the brackish marsh. This vegetation type was mapped immediately south of the parking lot and made up a very small portion of the study site. This area featured large, mature trees, primarily sycamore (Platanus racemosa) and occasional California black walnut (Juglans californica) and white alder (Alnus rhombifolia). This area was likely planted using species found in the riparian forest upstream, and may receive supplemental water from irrigation or parking lot runoff Disturbed Coastal Dunes A small area of disturbed coastal sand dune was mapped at the far eastern edge of the survey site, above the exposed mud flat. Pink sand verbena (Abronia umbellata) was mixed with silver beach bur (Ambrosia chamissonis), but was also mixed with non-native hottentot fig and Bermuda grass (Cynodon dactylon) Non-native Grassland Non-native grassland was mapped in a very small area near the edge of the trail south of the parking lot. This was a highly disturbed corner vegetated predominantly by weedy bromes (Bromus madritensis L. ssp. rubens, B. diandrus, and B. hordeaceus), as well as wild oat (Avena fatua). A small number of western ragweed were also mixed with the grasses Disturbed Habitat This descriptor was used to characterize a small patch of bare ground immediately south of the parking lot entrance road. It was predominantly bare ground supporting no distinct vegetation community. October 6, 2005 Malibu Mouse ENC

12 Mud Flat Due to the recent breach of the sand berm at the mouth of Malibu Lagoon, the majority of areas previously inundated were exposed mud flat at the time of the survey. Areas mapped as mud flat were unvegetated. While mud flats are typically characterized by finer grained, less mobile sediment particles, in this instance the exact location where mud flat transitioned into sand bar and sand beach was difficult to pinpoint. Therefore, in general, all areas that had been previously inundated and were unvegetated were mapped at mudflat, regardless of their constituent grain size Sand Beach/Sand Bar Areas that were clearly composed of coarser grained particles, resulting from higher energy transport of sand near the mouth of the lagoon, were mapped as sand bar. Large, unvegetated areas of open beach were mapped as sand beach Open Water Open water was mapped in all unvegetated areas that had not been de-watered by the breach of the sand berm. Open water was generally very shallow and persisted only in the deeper channels of the lagoon basins. Although this habitat accounted for the largest acreage in the survey area, this area will fluctuate significantly based on hydrological conditions. Loss of open water through drainage will be balanced by an increase in mud flat Urban/Developed The areas designated at Urban/Developed are comprised of the paved parking lot, access roads, access trails, and the grassy park area off the parking lot Trap Survey Findings Trap Site Descriptions The trapping effort was focused on sampling habitats potentially occupied by small mammals. Therefore, traplines were placed in most scrub habitats (Figure 3). Water, mudflats, sandy beach, and human-created habitats were not trapped. Sycamore alder woodland and baccharis scrub habitats were not trapped. Trapline A was set in a mix of southern willow scrub, mulefat scrub, and atriplex scrub habitats (Photo 1). A few traps were placed adjacent to mudflat habitat (Photo 2). Cover ranged from very dense scrub cover to bare ground along pathways. Trapline B was set mainly in southern coastal salt marsh and mulefat scrub (Photo 3). A few traps were placed in Venturan coastal sage scrub. Cover ranged from very dense in the coastal salt marsh to moderately dense in the scrub habitats (Photo 4). October 6, 2005 Malibu Mouse ENC

13 A B C D Source: Merkel & Associates 2004 Figure 3 Trapline Locations N Meters (approximate) Malibu Lagoon Restoration and Enhancement Project Small Mammal Trapping Assessment Malibu, California Photo 1. Hiking trail in willow/atriplex scrub habitat. October 6, 2005 Malibu Mouse ENC

14 Photo 2. Mud flat/mulefat scrub ecotone. Photo 3. Coastal salt marsh/freshwater marsh. October 6, 2005 Malibu Mouse ENC

15 Photo 4. Mulefat scrub. Note density of scrub and ground cover. Trapline C was set in atriplex scrub and southern coastal salt marsh (Photo 5). Cover was dense in both habitats. Trapline D was set in mixed scrub (Photo 6). A few traps were placed at the ecotone with the sand beach (Photo 7). Scrub cover was sparse, especially in the ecotone Trapping Survey Results Trapping success was low over the entire trapping period. Only one small mammal species, the black rat (Rattus rattus) was trapped during the survey period. Table 1 provides summary information on the trapping results. Photo 5. Southern coastal salt marsh. October 6, 2005 Malibu Mouse ENC

16 Photo 6. Mixed scrub habitat. Photo 7. Sandy ecotone between beach and scrub habitat. October 6, 2005 Malibu Mouse ENC

17 Table 1. Trapping Results for the Malibu Lagoon Black Rat Savannah Sparrow Trap Site Number of Trap Nights Rattus rattus Passerculus sandwichensis A B C D Totals Discussion Very little information is available regarding small mammals and salt marsh habitats in southern California. Most researchers appear to agree that salt marsh habitats are unfavorable for most small mammals (Bertness et al 1987, Dr. Brad Blood, personal communication, September 15, 2005). The salt content of many of the plant species is relatively high, making it difficult for small mammals to properly digest plant materials (Bertness et al 1987). In addition, many small mammals extract much of their water from plant material (Ingles 1965, Reichman and Price 1993). With a high salt content, the water in seeds and vegetative parts of plants create an osmotic imbalance in cellular water uptake such that small mammals cannot easily use the moisture in the plants. Based on the field survey and the trapping results, the Malibu Lagoon provides very poor quality habitat for small mammals. Most of the available scrub habitat is very dense at ground level as well as higher up, and the southern coastal salt marsh is almost entirely covered by pickleweed (Salicornia virginica) with very little bare ground exposed. Small mammals generally prefer more open scrub habitats with low openings and sparse ground cover (Grinnell 1933, Ingles 1965). In addition, the Lagoon is almost entirely surrounded by either water (open ocean) or development (housing and commercial). Malibu Creek provides the only connection to upland habitats, and it is severely restricted as it crosses under the Pacific Coast Highway. It is possible that other species, such as the deer mouse and the meadow mouse, are present in the Lagoon, but are at such low numbers that capture is difficult. It is also possible that more species of small mammal exist in the upland areas around Malibu Creek, but only infrequently come onto the Lagoon to forage. October 6, 2005 Malibu Mouse ENC

18 6.0 References Bertness, M.D., C. Wise and A.M. Ellison, Consumer pressure and seed set in a salt marsh perennial plant community. Oecologia, Volume 71, Number 2, pp Burt, W. H., A Field Guide to the Mammals in North American North of Mexico. Houghton Mifflin Company, Boston, Massachusetts. California Department of Fish and Game, Special Animals. The Resources Agency, Department of Fish and Game, Sacramento, California. Grenfell, W. E., M. D. Parisi, and D. McGriff, A Check-list of the Amphibians, Reptiles, Birds and Mammals of California. California Wildlife Habitat Relationship System, California Department of Fish and Game, Sacramento, California. Grinnell, J., Review of the Recent Mammal Fauna of California. University of California Publications in Zoology. 40: Hall, E. R., The Mammals of North America, Volumes I and II. John Wiley and Sons, New York, New York. Hickman, J. C., ed The Jepson Manual: Higher Plants of California. University of California Press. Ingles, L. G., Mammals of the Pacific States. Stanford University Press, Stanford, California. Johnson, R.F Predation by short-eared owls on a salicornia salt marsh. The Wilson Bulletin, Volume 68, No 2. pp Merkel & Associates, Malibu Lagoon Vegetation Communities and Wetland Delineation. Report prepared for Moffatt & Nichol, Long Beach, California. Reichman, O. and M. Price Ecological Aspects of Heteromyid Foraging, In. Biology of the Heteromyide, H. Genoways and J. Brown, eds. American Society of Mammalogists. U.S. Fish and Wildlife Service, Review of plant and animal taxa for listing as endangered or threatened species; notice of review. Federal Register Vol. 61, No. 40. Williams, D. F., Mammalian Species of Special Concern in California. Wildlife Management Division Administrative Report Prepared for The Resources Agency, California Department of Fish and Game. Zeiner, D. C., W. F. Laundenslayer, Jr., K. E. Mayer and M. White, California s Wildlife, Volume III Mammals, The Resources Agency, Department of Fish and Game, Sacramento, California. October 6, 2005 Malibu Mouse ENC

19 7.0 Personal Communication Dr. Brad Blood, Psomas Associates, Costa Mesa, California. Mr. Philippe Vergne, ENVIRA, Ramona, California October 6, 2005 Malibu Mouse ENC